1. FIELD OF THE INVENTION
The present invention relates generally to motor vehicle economizing devices, and it relates more specifically to methods and apparatus for disabling a battery charging system when the vehicle's engine is under load and the battery is already charged to a predetermined threshold level.
2. DESCRIPTION OF PRIOR ART
The general principles of internal combustion engines are widely known, including the fact such engines have a characteristic curve that relates the brake horsepower of the engine to the engine RPM (revolutions per minute). At low RPM, the available brake horsepower is only a small fraction of the total horsepower that the engine can develop. When the engine is operated under heavy load, especially at low RPM, such as occurs when an engine-powered vehicle is accelerating from a full stop, or during rapid acceleration of the vehicle from a moderate speed to a relatively high speed, or when operating the vehicle for a prolonged period under conditions that resemble acceleration demands, such as climbing steep hills, the engine is operating at an inherently inefficient condition. Under such inefficient conditions, more fuel is added to the engine to increase its horsepower output. However, a significant portion of the fuel is not burned, resulting in both wasted fuel and high atmospheric pollution by the vehicle's exhaust gas. Any load component or drag that can be removed from the engine during its operation in such an inefficient condition will allow the engine to achieve a more efficient and cleaner operation sooner.
In actual use, few auxiliary loads which an engine drives in a conventional motor vehicle are necessary on a continuous basis. By coordinating these loads with the operating regime of the engine, engine efficiency can be improved and pollution reduced.
Many control devices for automobile engines exist. Some of such devices attempt to achieve smooth, stable, or efficient engine operation. Some attempt to increase gasoline mileage, while others attempt to reduce pollution. A few devices attempt to decrease engine loads under certain conditions. None of such previous devices known to these inventors has attempted to eliminate or reduce a primary source of drag on the engine that exists in nearly every automobile or truck that uses an internal combustion engine, that of the alternator or generator.